Lighting fixtures currently in use in residential, industrial, outdoor or other architectural applications typically utilize clear or frosted lenses to cover the orifice of the lighting fixture to primarily serve as both a safety shield for the inner light source and its related componentry and as a means to pitch light rays in a predetermined direction throughout a given area.
However, the clear lenses suffer from the inability of aesthetically being able to conceal the inner componentry of the light source, thus limiting the lighting fixture's aesthetic appeal in certain design environments. In the case of frosted lenses they do effectively conceal the inner componentry of the lighting fixture, but however achieves its objectives by placing only one type of conventional "white-haze" coating over the lens.
In addition, there are some light bulbs that have colored glass housings surrounding their filaments which cast a functional red, blue, yellow, etc. light when said light source is activated.
However, when said source is not activated this permanent glass tint is unable to alter its functional coloration to that of another coloration (or transparent) to better suit its interior or exterior design environments.